Hi, the linux build worked for me once I changed some files's rights ("chmod +x assetflip.sh Engine/Binaries/Linux/EpicWebHelper"). I'm pretty sure zip archives don't store if files are supposed to be executable, but tar archives do and are standard for sharing linux software.
Also, library files (*.so) aren't stripped of debug informations which is why the linux build is 4gb once extracted.
I have no idea how Unreal Engine exports linux builds and if it's easy to fix those issues, but hopefully this helps someone play this game :p.